Selective hydrogenation catalyst and methods of making and using same

ABSTRACT

A composition comprising a supported hydrogenation catalyst comprising palladium and an organophosphorous compound, the supported hydrogenation catalyst being capable of selectively hydrogenating highly unsaturated hydrocarbons to unsaturated hydrocarbons. A method of making a selective hydrogenation catalyst comprising contacting a support with a palladium-containing compound to form a palladium supported composition, contacting the palladium supported composition with an organophosphorus compound to form a catalyst precursor, and reducing the catalyst precursor to form the catalyst. A method of selectively hydrogenating highly unsaturated hydrocarbons to an unsaturated hydrocarbon enriched composition comprising contacting a supported catalyst comprising palladium and an organophosphorous compound with a feed comprising highly unsaturated hydrocarbon under conditions suitable for hydrogenating at least a portion of the highly unsaturated hydrocarbon feed to form the unsaturated hydrocarbon enriched composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 14/134,282 filed on Dec. 19, 2013, which is adivisional of and claims priority to U.S. patent application Ser. No.12/710,781 filed on Feb. 23, 2010, now U.S. Pat. No. 8,633,127, whichclaims priority to U.S. Provisional Patent Application Ser. No.61/157,491, filed Mar. 4, 2009 and all of which entitled “SelectiveHydrogenation Catalyst and Methods of Making and Using Same,” each ofwhich is hereby incorporated herein by reference in its entirety for allpurposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

1. Technical Field

The present disclosure relates to the production of unsaturatedhydrocarbons, and more particularly to a selective hydrogenationcatalyst and methods of making and using same.

2. Background

Unsaturated hydrocarbons such as ethylene and propylene are oftenemployed as feedstocks in preparing value added chemicals and polymers.Unsaturated hydrocarbons may be produced by pyrolysis or steam crackingof hydrocarbons including hydrocarbons derived from coal, hydrocarbonsderived from synthetic crude, naphthas, refinery gases, ethane, propane,butane, and the like. Unsaturated hydrocarbons produced in these mannersusually contain small proportions of highly unsaturated hydrocarbonssuch as acetylenes and diolefins that adversely affect the production ofsubsequent chemicals and polymers. Thus, to form an unsaturatedhydrocarbon product such as a polymer grade monoolefin, the amount ofacetylenes and diolefins in the monoolefin stream is typically reduced.For example, in polymer grade ethylene, the acetylene content typicallyis less than about 2 ppm.

One technique commonly used to reduce the amount of acetylenes anddiolefins in an unsaturated hydrocarbon stream primarily comprisingmonoolefins involves selectively hydrogenating the acetylenes anddiolefins to monoolefins. This process is selective in thathydrogenation of the monoolefin and the highly unsaturated hydrocarbonsto saturated hydrocarbons is minimized. For example, the hydrogenationof ethylene or acetylene to ethane is minimized.

One challenge to the selective hydrogenation process is the potentialfor runaway reactions that lead to the uncontrollable reduction ofethylene to ethane. One methodology to minimize runaway reactions is toincrease the amount of selectivity enhancers in the hydrogenationcatalyst. Thus, catalyst preparations may comprise one or moreselectivity enhancers. Selectivity enhancers are materials such asalkali metal halides that increase the catalyst selectivity for thehydrogenation of highly unsaturated olefins to unsaturated olefins. Theuse of additional amounts of selectivity enhancers, also termedincreased loadings, may lead to improved catalyst selectivity; however,the increased loadings may have drawbacks such as decreased catalystactivity. Therefore, a need exists for a hydrogenation catalyst that hasa desired selectivity and activity.

SUMMARY

Disclosed herein is a composition comprising a supported hydrogenationcatalyst comprising palladium and an organophosphorous compound, thesupported hydrogenation catalyst being capable of selectivelyhydrogenating highly unsaturated hydrocarbons to unsaturatedhydrocarbons.

Also disclosed herein is a method of making a selective hydrogenationcatalyst comprising contacting a support with a palladium-containingcompound to form a palladium supported composition, contacting thepalladium supported composition with an organophosphorus compound toform a catalyst precursor, and reducing the catalyst precursor to formthe catalyst.

Further disclosed herein is a method of selectively hydrogenating highlyunsaturated hydrocarbons to an unsaturated hydrocarbon enrichedcomposition comprising contacting a supported catalyst comprisingpalladium and an organophosphorous compound with a feed comprisinghighly unsaturated hydrocarbon under conditions suitable forhydrogenating at least a portion of the highly unsaturated hydrocarbonfeed to form the unsaturated hydrocarbon enriched composition.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1 depicts a process flow diagram of an embodiment of a selectivehydrogenation process.

FIG. 2 is a plot of ethylene weight percentage in reactor effluent as afunction of temperature for the sample from Example 1.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

In an embodiment, a method of making a selective hydrogenation catalystcomprises contacting an inorganic catalyst support with apalladium-containing compound to form a palladium supported compositionand contacting the palladium supported composition with anorganophosphorus compound. Herein, the disclosure will focus on the useof phosphine oxides, phosphates, phosphinates, and phosphonates as theorganophosphorus compound, although phosphines phosphites, phosphinites,and phosphonites are also contemplated organophosphorus compoundprecursors and will be described in more detail later herein. In anembodiment, the organophosphorus compound functions to increase theselectivity of the hydrogenation catalyst for the conversion of a highlyunsaturated hydrocarbon to an unsaturated hydrocarbon. Herein, suchcatalysts are termed palladium, organophosphorus supported catalysts(PPSC).

The PPSC may be used for selectively hydrogenating highly unsaturatedhydrocarbons to unsaturated hydrocarbons. As used herein, a highlyunsaturated hydrocarbon is defined as a hydrocarbon containing a triplebond, two conjugated carbon-carbon double bonds, or two cumulativecarbon-carbon double bonds. As used herein, an unsaturated hydrocarbonis defined as a hydrocarbon containing an isolated carbon-carbon doublebond. Examples of highly unsaturated hydrocarbons include withoutlimitation acetylene, methylacetylene, and propadiene. Examples ofunsaturated hydrocarbons include ethylene and propylene. It is alsounderstood that the term “catalyst” refers to the support together withthe materials impregnated in or on the support.

In an embodiment, the PPSC may comprise an inorganic support such as forexample and without limitation aluminas, silicas, titanias, zirconias,aluminosilicates (e.g., clays, ceramics, and/or zeolites), spinels(e.g., zinc aluminate, zinc titanate, and/or magnesium aluminate), orcombinations thereof. In an embodiment, the PPSC comprises an aluminasupport. In some embodiments, the alumina support comprises an alpha(α)-alumina support.

The inorganic support may have a surface area of from about 2 to about100 square meters per gram (m²/g), alternatively of from about 2 m²/g toabout 75 m²/g, alternatively of from about 3 m²/g to about 50 m²/g,alternatively of from about 4 m²/g to about 25 m²/g, alternatively offrom about 5 m²/g to about 10 m²/g. The surface area of the support maybe determined using any suitable method. An example of a suitable methodincludes the Brunauer, Emmett, and Teller (“BET”) method, which measuresthe quantity of nitrogen adsorbed on the support. Alternatively, thesurface area of the support can be measured by a mercury intrusionmethod such as is described in ASTM UOP 578-02, entitled “Automated PoreVolume and Pore Size Distribution of Porous Substances by MERCURYPorosimetry,” which is incorporated herein by reference in its entirety.

Particles of the inorganic support generally have an average diameter offrom about 1 mm to about 10 mm, alternatively from about 2 mm to about 6mm, alternatively from about 2 mm to about 4 mm, alternatively fromabout 4 mm to about 6 mm and can have any suitable shape. In anembodiment, the shape of the inorganic support may be cylindrical. In analternative embodiment, the shape of the inorganic support may bespherical.

In an embodiment, the inorganic support may be present in an amount suchthat it comprises the balance of the PPSC when all other components areaccounted for.

In an embodiment, the PPSC comprises palladium. The palladium may beadded to the PPSC by contacting the inorganic support with apalladium-containing compound to form a palladium supported compositionas will be described in more detail later herein. Examples of suitablepalladium-containing compounds include without limitation palladiumchloride, palladium nitrate, ammonium hexachloropalladate, ammoniumtetrachlopalladate, palladium acetate, palladium bromide, palladiumiodide, tetraamminepalladium nitrate, or combinations thereof. In anembodiment, the palladium-containing compound is a component of anaqueous solution. An example of palladium-containing solution suitablefor use in this disclosure includes without limitation a solutioncomprising palladium metal.

In an embodiment, the PPSC may be prepared using a palladium-containingcompound in an amount of from about 0.005 wt. % to about 5 wt. % basedon the total weight of the PPSC, alternatively from about 0.01 wt. % toabout 3 wt. %, alternatively from about 0.02 wt. % to about 1 wt. %,alternatively from about 0.02 wt. % to about 0.04 wt. %, alternativelyfrom about 0.03 wt. % to about 0.05 wt. %. The amount of palladiumincorporated into the PPSC may be in the range described herein for theamount of palladium-containing compound used to prepare the PPSC.

In an embodiment, the PPSC comprises an organophosphorus compound. In anembodiment, the organophosphorus compound can be represented by thegeneral formula of (R)_(x)(OR′)_(y)P═O; wherein x and y are integersranging from 0 to 3 and x plus y equals 3; wherein each R may behydrogen, a hydrocarbyl group, or combinations thereof; and wherein eachR′ may a hydrocarbyl group. In some embodiments, the organophosphoruscompound may include compounds such as phosphine oxides, phosphinates,phosphonates, phosphates, or combinations of any of the foregoing. Forpurposes of this application, the term “hydrocarbyl(s)” or “hydrocarbylgroup(s)” is used herein in accordance with the definition specified byIUPAC: as a univalent group or groups derived by the removal of onehydrogen atom from a carbon atom of a “hydrocarbon.” A hydrocarbyl groupcan be an aliphatic, inclusive of acyclic and cyclic groups. Ahydrocarbyl group can include rings, ring systems, aromatic rings, andaromatic ring systems. Hydrocarbyl groups may include, by way ofexample, aryl, alkyl, cycloalkyl, and combinations of these groups,among others. Hydrocarbyl groups may be linear or branched unlessotherwise specified. For the purposes of this application, the terms“alkyl,” or “cycloalkyl” refers to a univalent group derived by removalof a hydrogen atom from any carbon atom of an alkane. For the purposesof this application, the terms “aryl,” or “arylene” refers to aunivalent group derived by removal of a hydrogen atom from any carbonatom of an aryl ring.

In an embodiment, the hydrocarbyl group can have from 1 to 30 carbonatoms, alternatively from 2 to 20 carbon atoms, alternatively from 3 to15 carbon atoms. In other embodiments, the hydrocarbyl group can havefrom about 6 to about 30 carbon atoms, alternatively from about 6 toabout 20 carbon atoms, alternatively from about 6 to about 15 carbonatoms.

Generally, the alkyl group for any feature which calls for an alkylgroup described herein can be a methyl, ethyl, n-propyl(1-propyl),isopropyl (2-propyl), n-butyl(1-butyl), sec-butyl(2-butyl), isobutyl(2-methyl-1-propyl), tert-butyl (2-methyl-2-propyl), n-pentyl(1-pentyl),2-pentyl, 3-pentyl, 2-methyl-1-butyl, tert-pentyl (2-methyl-2-butyl),3-methyl-1-butyl, 3-methyl-2-butyl, neo-pentyl (2,2-dimethyl-1-propyl),n-hexyl(1-hexyl) group. Persons having ordinary skill in the art withthe aids of this disclosure will readily recognize which alkyl grouprepresents primary, secondary, or tertiary alkyl groups.

Organophosphorus compounds described herein are not considered toencompass elemental phosphorus, or inorganic phosphorus compounds,except that which may be produced during the preparation of the PPSCdescribed herein. Inorganic phosphorus compounds encompass monobasic,dibasic, and tribasic phosphates such as tribasic potassium phosphate(K₃PO₄), tribasic sodium phosphate (Na₃PO₄), dibasic potassium phosphate(K₂HPO₄), dibasic sodium phosphate (Na₂HPO₄), monobasic potassiumphosphate (KH₂PO₄), monobasic sodium phosphate (NaH₂PO₄). Inorganicphosphorus compounds also encompass the corresponding phosphorus acid ofabove mentioned salts. Inorganic phosphorus compounds also encompassanionic inorganic phosphorus compounds containing pentavalentphosphorus, and halogens. Examples of anionic inorganic phosphoruscompounds include sodium and potassium hexafluorophosphate.

An organophosphorus compound suitable for use in this disclosure may befurther characterized by a low-boiling point wherein a low boiling pointrefers to a boiling point of about 100° C. Alternatively, anorganophosphorus compound suitable for use in this disclosure may befurther characterized by a high boiling point wherein a high boilingpoint refers to a boiling point of equal to or greater than about 300°C.

In an embodiment, the organophosphorus compound comprises a phosphineoxide which can be represented by the general formula of (R)₃P═O;wherein each R may be hydrogen, a hydrocarbyl group, or combinationsthereof. Examples of phosphine oxides suitable for use in thisdisclosure include without limitation butyldiethylphosphine oxide,butyldimethylphosphine oxide, butyldiphenylphosphine oxide,butyldipropylphosphine oxide, decyldiethylphosphine oxide,decyldimethylphosphine oxide, decyldiphenylphosphine oxide,dibutyl(2-methylphenyl)-phosphine oxide,diethyl(3-methylphenyl)-phosphine oxide, ethyldioctylphosphine oxide,ethyldibutylphosphine oxide, ethyldimethylphosphine oxide,ethyldiphenylphosphine oxide, ethyldipropylphosphine oxide,heptyldibutylphosphine oxide, heptyldiethylphosphine oxide,heptyldimethyl phosphine oxide, heptyldipentylphosphine oxide,heptyldiphenylphosphine oxide, hexyldibutylphosphine oxide,hexyldiethylphosphine oxide, hexyldimethyl phosphine oxide,hexyldipentylphosphine oxide, hexyldiphenylphosphine oxide,methylbis(4-methylphenyl)-phosphine oxide, methyldibutylphosphine oxide,methyldidecylphosphine oxide, methyldiethylphosphine oxide,methyldiphenylphosphine oxide, methyldipropylphosphine oxide,octyldimethylphosphine oxide, octyldiphenylphosphine oxide,pentyldibutylphosphine oxide, pentyldiethylphosphine oxide,pentyldimethylphosphine oxide, pentyldiphenylphosphine oxide,phenyldibutylphosphine oxide, phenyldiethylphosphine oxide,phenyldimethylphosphine oxide, phenyldipropylphosphine oxide,propyldibutylphosphine oxide, propyldimethylphosphine oxide,propyldiphenylphosphine oxide, tris(2,6-dimethylphenyl)-phosphine oxide,tris(2-methylphenyl)phosphine oxide, tris(4-methylphenyl)-phosphineoxide, tris[4-(1,1-dimethylethyl)phenyl]-phosphine oxide,(1-methylethyl)diphenyl-phosphine oxide,4-(diphenylmethyl)phenyl]diphenyl-phosphine oxide,bis(2-methylphenyl)(2-methylpropyl)-phosphine oxide, or combinationsthereof. In some embodiments, the phosphine oxides suitable for use inthis disclosure include without limitation tributylphosphine oxide,triethylphosphine oxide, triheptylphosphine oxide, trimethylphosphineoxide, trioctylphosphine oxide, tripentylphosphine oxide,tripropylphosphine oxide, triphenylphosphine oxide, or combinationsthereof.

In an embodiment, the organophosphorus compound comprises an organicphosphate which can be represented by the general formula of (OR′)₃P═O;wherein each R′ may a hydrocarbyl group. Examples of phosphates suitablefor use in this disclosure include without limitation(1-methylethyl)diphenyl phosphate, 2-ethylphenyldiphenyl phosphate,4-(diphenylmethyl)phenyl]diphenyl phosphate,bis(2-methylphenyl)(2-methylpropyl)phosphate, butyldiethylphosphate,butyldimethylphosphate, butyldiphenylphosphate, butyldipropylphosphate,crecyldiphenylphosphate, decyldiethylphosphate, decyldimethylphosphate,decyldiphenylphosphate, dibutyl(2-methylphenyl)phosphate,diethyl(3-methylphenyl)phosphate, ethyldibutylphosphate,ethyldimethylphosphate, ethyldioctylphosphate, ethyldiphenylphosphate,ethyldipropylphosphate, heptyldibutylphosphate, heptyldiethylphosphate,heptyldimethyl phosphate, heptyldipentylphosphate,heptyldiphenylphosphate, hexyldibutylphosphate, hexyldiethylphosphate,hexyldimethyl phosphate, hexyldipentylphosphate, hexyldiphenylphosphate,methylbis(4-methylphenyl)phosphate, methyldibutylphosphate,methyldidecylphosphate, methyldiethylphosphate, methyldiphenylphosphate,methyldipropylphosphate, octyldimethylphosphate, octyldiphenylphosphate,pentyldibutylphosphate, pentyldiethylphosphate, pentyldimethylphosphate,pentyldiphenylphosphate, phenyldibutylphosphate, phenyldiethylphosphate,phenyldimethylphosphate, phenyldipropylphosphate, propyldibutylphosphate, propyldimethylphosphate, propyldiphenylphosphate,tri(2,3-dichloropropyl)phosphate, tri(2,6-dimethylphenyl)phosphate,tri(2-chloroethyl)phosphate, tri(nonylphenyl)phosphate,tris(2,6-dimethylphenyl)phosphate, tris(2-methylphenyl)phosphate,tris(4-methylphenyl)phosphate,tris[4-(1,1-dimethylethyl)phenyl]phosphate, or combinations thereof. Insome embodiments, the phosphates suitable for use in this disclosureinclude without limitation tributylphosphate, tricresyl phosphate,tricyclohexyl phosphate, tridecylphosphate, triethylphosphate,triheptylphosphate, triisopropyl phosphate, trimethylphosphate,trioctadecyl phosphate, trioctylphosphate, tripentylphosphate,triphenylphosphate, tripropylphosphate, trixylylphosphate, orcombinations thereof.

In an embodiment, the organophosphorus compound comprises a phosphinate,which can be represented by the general formula of (R)₂(OR′)P═O; whereineach R may be hydrogen, a hydrocarbyl group, or combinations thereof;and wherein each R′ may a hydrocarbyl group. Examples of phosphinatessuitable for use in this disclosure include without limitation butylbutylphosphinate, butyl dibutylphosphinate, butyl diethylphosphinate,butyl diphenylphosphinate, butyl dipropylphosphinate, butylethylphosphinate, butyl heptylphosphinate, butyl hexylphosphinate, butylpentylphosphinate, butyl phenylphosphinate, butyl propylphosphinate,decyl pentylphosphinate, butyl butylpentylphosphinate, ethylbutylphosphinate, ethyl decylphosphinate, ethyl dibutylphosphinate,ethyl diethylphosphinate, ethyl dimethylphosphinate, ethyldiphenylphosphinate, ethyl dipropylphosphinate, ethyl ethylphosphinate,ethyl heptylphosphinate, ethyl hexylphosphinate, ethyl octylphosphinate,ethyl pentylphosphinate, ethyl phenylphosphinate, ethylpropylphosphinate, heptyl dibutylphosphinates, heptyl pentylphosphinate,heptylphosphinate, hexyl dibutylphosphinate, hexyl pentylphosphinate,isopropyl diphenylphosphinate, methyl butylphosphinate, methyldecylphosphinate, methyl dibutylphosphinate, methyl diethylphosphinate,methyl dimethylphosphinate, methyl diphenylphosphinates, methyldipropylphosphinate, methyl ethylphosphinate, methyl heptylphosphinate,methyl hexylphosphinate, methyl octylphosphinate, methylpentylphosphinate, methyl phenylphosphinate, methyl propylphosphinate,octyl pentylphosphinate, octylphosphinate, pentyl dibutylphosphinate,pentylphosphinate, phenyl butylphosphinate, phenyl decylphosphinate,phenyl dibutylphosphinate, phenyl diethylphosphinate, phenyldiethylphosphinate, phenyl dimethylphosphinate, phenyldiphenylphosphinate, phenyl diphenylphosphinate, phenyldipropylphosphinate, phenyl ethylphosphinate, phenyl heptylphosphinate,phenyl hexylphosphinate, phenyl octylphosphinate, phenylpentylphosphinate, phenyl pentylphosphinate, phenyl phenylphosphinate,phenyl propylphosphinate, phenylphosphinate, propyl diphenylphosphinate,or combinations thereof.

In an embodiment, the organophosphorus compound comprises a phosphonate,which can be represented by the general formula of (R)(OR′)₂P═O; whereineach R may be hydrogen, a hydrocarbyl group, or combinations thereof;and wherein each R′ may a hydrocarbyl group. Examples of phosphonatessuitable for use in this disclosure include without limitation(1-methylethyl)diphenyl phosphonate, 2-ethylphenyldiphenyl phosphonate,4-(diphenylmethyl)phenyl]diphenyl phosphonate, bis(2-methylphenyl)(2-methylpropyl)phosphonate, butyldiethylphosphonate,butyldimethylphosphonate, butyldiphenylphosphonate,butyldipropylphosphonate, crecyldiphenylphosphonate,decyldiethylphosphonate, decyldimethylphosphonate,decyldiphenylphosphonate, dibutyl(2-methylphenyl)phosphonate,diethyl(3-methylphenyl)phosphonate, ethyldibutylphosphonate,ethyldimethylphosphonate, ethyldioctylphosphonate,ethyldiphenylphosphonate, ethyldipropylphosphonate,heptyldibutylphosphonate, heptyldiethylphosphonate, heptyldimethylphosphonate, heptyldipentylphosphonate, heptyldiphenylphosphonate,hexyldibutylphosphonate, hexyldiethylphosphonate, hexyldimethylphosphonate, hexyldipentylphosphonate, hexyldiphenylphosphonate,methylbis(4-methylphenyl)phosphonate, methyldibutylphosphonate,methyldidecylphosphonate, methyldiethylphosphonate,methyldiphenylphosphonate, methyldipropylphosphonate,octyldimethylphosphonate, octyldiphenylphosphonate,pentyldibutylphosphonate, pentyldiethylphosphonate,pentyldimethylphosphonate, pentyldiphenylphosphonate,phenyldibutylphosphonate, phenyldiethylphosphonate,phenyldimethylphosphonate, phenyldipropylphosphonate,propyldibutylphosphonate, propyldimethylphosphonate,propyldiphenylphosphonate, tri(2,3-dichloropropyl)phosphonate,tri(2,6-dimethylphenyl)phosphonate, tri(2-chloroethyl)phosphonate,tri(nonylphenyl)phosphonate, tris(2,6-dimethylphenyl)phosphonate,tris(2-methylphenyl)phosphonate, tris(4-methylphenyl)phosphonate,tris[4-(1,1-dimethylethyl)phenyl]phosphonate, or combinations thereof.In some embodiments, the phosphonates suitable for use in thisdisclosure include without limitation tributylphosphonate, tricresylphosphonate, tricyclohexyl phosphonate, tridecylphosphonate,triethylphosphonate, triheptylphosphonate, triisopropyl phosphonate,trimethylphosphonate, trioctadecyl phosphonate, trioctylphosphonate,tripentylphosphonate, triphenylphosphonate, tripropylphosphonate,trixylylphosphonate, or combinations thereof.

In an embodiment, the PPSC comprises a precursor to the organophosphoruscompound. The organophosphorus compound precursor may comprise anymaterial which may be converted to the organophosphorus compound whichactivates the PPSC under the conditions to which the hydrogenationcatalyst is exposed and that is compatible with the other components ofthe PPSC. In an embodiment, the organophosphorus compound precursor canbe represented by the general formula of (R)_(x)(OR′)_(y)P; wherein xand y are integers ranging from 0 to 3 and x plus y equals 3; whereineach R may be hydrogen, a hydrocarbyl group, or combinations thereof;and wherein each R′ may a hydrocarbyl group. The organophosphoruscompound precursor may include without limitation phosphines,phosphites, phosphinites, phosphonites, or combinations thereof. In anembodiment, the organophosphorus compound precursor comprises aphosphine that can form a phosphine oxide when exposed to an oxidizingagent and/or temperatures greater than about 20° C. In an embodiment,the organophosphorus compound precursor comprises a phosphite that canform a phosphate when exposed to an oxidizing agent and/or temperaturesgreater than about 20° C. In an embodiment, the organophosphoruscompound precursor comprises a phosphinite that can form a phosphinatewhen exposed to oxidizing agent and/or temperatures greater than about20° C. In an embodiment, the organophosphorus compound precursorcomprises a phosphonite that can form a phosphonate when exposed to airand/or temperatures greater than about 20° C.

In an embodiment, the organophosphorus compound comprises phosphines,which can be represented by the general formula of (R)₃P; wherein each Rmay be hydrogen, a hydrocarbyl group, or combinations thereof. Examplesof phosphines suitable for use as phosphine oxide precursors in thisdisclosure include without limitation (1-methylethyl)diphenylphosphine,2-ethylphenyldiphenyl phosphine,4-(diphenylmethyl)phenyl]diphenylphosphine, bis(2-methylphenyl)(2-methylpropyl)phosphine, butyldiethylphosphine,butyldimethylphosphine, butyldiphenylphosphine, butyldipropylphosphine,crecyldiphenylphosphine, cyclohexyldiphenylphosphine,decyldiethylphosphine, decyldimethylphosphine, decyldiphenylphosphine,dibutyl(2-methylphenyl)phosphine, dicyclohexylphenylphosphine,diethyl(3-methylphenyl)phosphine, ethyldibutylphosphine,ethyldimethylphosphine, ethyldioctylphosphine, ethyldiphenylphosphine,ethyldipropylphosphine, heptyldibutylphosphine, heptyldiethylphosphine,heptyldimethyl phosphine, heptyldipentylphosphine,heptyldiphenylphosphine, hexyldibutylphosphine, hexyldiethylphosphine,hexyldimethyl phosphine, hexyldipentylphosphine, hexyldiphenylphosphine,methylbis(4-methylphenyl)phosphine, methyldibutylphosphine,methyldidecylphosphine, methyldiethylphosphine, methyldiphenylphosphine,methyldipropylphosphine, octyldimethylphosphine, octyldiphenylphosphine,pentyldibutylphosphine, pentyldiethylphosphine, pentyldimethylphosphine,pentyldiphenylphosphine, phenyldibutylphosphine, phenyldiethylphosphine,phenyldimethylphosphine, phenyldipropylphosphine,propyldibutylphosphine, propyldimethylphosphine,propyldiphenylphosphine, tri(2,3-dichloropropyl)phosphine,tri(2,6-dimethylphenyl)phosphine, tri(2-chloroethyl)phosphine,tri(nonylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine,tris(2-methylphenyl)phosphine, tris(4-methylphenyl)phosphine,tris(methoxyphenyl)phosphine,tris[4-(1,1-dimethylethyl)phenyl]phosphine, or combinations thereof. Insome embodiments, the phosphines suitable for use in this disclosureinclude without limitation tributylphosphine, tricresyl phosphine,tricyclohexyl phosphine, tridecylphosphine, triethylphosphine,triheptylphosphine, triisopropylphosphine, trimethylphosphine,trioctadecyl phosphine, trioctylphosphine, tripentylphosphine,triphenylphosphine, tripropylphosphine, tri-t-butylphosphine,tritolylphosphine, trixylylphosphine, or combinations thereof.

In an embodiment, the organophosphorus compound comprises phosphites,which can be represented by the general formula of (OR′)₃P; wherein eachR′ may a hydrocarbyl group. Examples of phosphites suitable for use asphosphate precursors in this disclosure include without limitation(1-methylethyl)diphenylphosphite, 2-ethylphenyldiphenyl phosphite,4-(diphenylmethyl)phenyl]diphenylphosphite,bis(2-methylphenyl)(2-methylpropyl)phosphite, butyldiethylphosphite,butyldimethylphosphite, butyldiphenylphosphite, butyldipropylphosphite,crecyldiphenylphosphite, cyclohexyldiphenylphosphite,decyldiethylphosphite, decyldimethylphosphite, decyldiphenylphosphite,dibutyl(2-methylphenyl)phosphite, dicyclohexylphenylphosphite,diethyl(3-methylphenyl)phosphite, ethyldibutylphosphite,ethyldimethylphosphite, ethyldioctylphosphite, ethyldiphenylphosphite,ethyldipropylphosphite, heptyldibutylphosphite, heptyldiethylphosphite,heptyldimethyl phosphite, heptyldipentylphosphite,heptyldiphenylphosphite, hexyldibutylphosphite, hexyldiethylphosphite,hexyldimethyl phosphite, hexyldipentylphosphite, hexyldiphenylphosphite,methylbis(4-methylphenyl)phosphite, methyldibutylphosphite,methyldidecylphosphite, methyldiethylphosphite, methyldiphenylphosphite,methyldipropylphosphite, octyldimethylphosphite, octyldiphenylphosphite,pentyldibutylphosphite, pentyldiethylphosphite, pentyldimethylphosphite,pentyldiphenylphosphite, phenyldibutylphosphite, phenyldiethylphosphite,phenyldimethylphosphite, phenyldipropylphosphite,propyldibutylphosphite, propyldimethylphosphite,propyldiphenylphosphite, tri(2-chloroethyl)phosphite,tri(nonylphenyl)phosphite, tris(2,3-dichloropropyl)phosphite,tris(2,6-dimethylphenyl)phosphite, tris(2-methylphenyl)phosphite,tris(4-methylphenyl)phosphite, tris(methoxyphenyl)phosphite,tris[4-(1,1-dimethylethyl)phenyl]phosphite, tri-t-butylphosphite, orcombinations thereof. In some embodiments, the phosphites suitable foruse in this disclosure include without limitation tributylphosphite,tricresyl phosphite, tricyclohexyl phosphite, tridecylphosphite,triethylphosphite, triheptylphosphite, triisopropylphosphite,trimethylphosphite, trioctadecyl phosphite, trioctylphosphite,tripentylphosphite, triphenylphosphite, tripropylphosphite,tritolylphosphite, trixylylphosphite, or combinations thereof.

In an embodiment, the organophosphorus compound comprises phosphinites,which can be represented by the general formula of (R)₂(OR′)₁P; whereineach R may be hydrogen, a hydrocarbyl group, or combinations thereof;and wherein each R′ may a hydrocarbyl group. Examples of phosphinitessuitable for use as phosphate precursors in this disclosure includewithout limitation (1-methylethyl)diphenylphosphinite,2-ethylphenyldiphenyl phosphinite,4-(diphenylmethyl)phenyl]diphenylphosphinite,bis(2-methylphenyl)(2-methylpropyl)phosphinite, butyldiethylphosphinite,butyldimethylphosphinite, butyldiphenylphosphinite,butyldipropylphosphinite, crecyldiphenylphosphinite,cyclohexyldiphenylphosphinite, decyldiethylphosphinite,decyldimethylphosphinite, decyldiphenylphosphinite,dibutyl(2-methylphenyl)phosphinite, dicyclohexylphenylphosphinite,diethyl(3-methylphenyl)phosphinite, ethyldibutylphosphinite,ethyldimethylphosphinite, ethyldioctylphosphinite,ethyldiphenylphosphinite, ethyldipropylphosphinite,heptyldibutylphosphinite, heptyldiethylphosphinite, heptyldimethylphosphinite, heptyldipentylphosphinite, heptyldiphenylphosphinite,hexyldibutylphosphinite, hexyldiethylphosphinite, hexyldimethylphosphinite, hexyldipentylphosphinite, hexyldiphenylphosphinite,methylbis(4-methylphenyl)phosphinite, methyldibutylphosphinite,methyldidecylphosphinite, methyldiethylphosphinite,methyldiphenylphosphinite, methyldipropylphosphinite,octyldimethylphosphinite, octyldiphenylphosphinite,pentyldibutylphosphinite, pentyldiethylphosphinite,pentyldimethylphosphinite, pentyldiphenylphosphinite,phenyldibutylphosphinite, phenyldiethylphosphinite,phenyldimethylphosphinite, phenyldipropylphosphinite,propyldibutylphosphinite, propyldimethylphosphinite,propyldiphenylphosphinite, tri(2-chloroethyl)phosphinite,tri(nonylphenyl)phosphinite, tris(2,3-dichloropropyl)phosphinite,tris(2,6-dimethylphenyl)phosphinite, tris(2-methylphenyl)phosphinite,tris(4-methylphenyl)phosphinite, tris(methoxyphenyl)phosphinite,tris[4-(1,1-dimethylethyl)phenyl]phosphinite, tri-t-butylphosphinite, orcombinations thereof. In some embodiments, the phosphinites suitable foruse in this disclosure include without limitation tributylphosphinite,tricresyl phosphinite, tricyclohexyl phosphinite, tridecylphosphinite,triethylphosphinite, triheptylphosphinite, triisopropylphosphinite,trimethylphosphinite, trioctadecyl phosphinite, trioctylphosphinite,tripentylphosphinite, triphenylphosphinite, tripropylphosphinite,tritolylphosphinite, trixylylphosphinite, or combinations thereof.

In an embodiment, the organophosphorus compound comprises phosphonites,which can be represented by the general formula of (R)₁(OR′)₂P; whereineach R may be hydrogen, a hydrocarbyl group, or combinations thereof;and wherein each R′ may a hydrocarbyl group. Examples of phosphonitessuitable for use as phosphate precursors in this disclosure includewithout limitation (1-methylethyl)diphenylphosphonite,2-ethylphenyldiphenyl phosphonite,4-(diphenylmethyl)phenyl]diphenylphosphonite,bis(2-methylphenyl)(2-methylpropyl)phosphonite, butyldiethylphosphonite,butyldimethylphosphonite, butyldiphenylphosphonite,butyldipropylphosphonite, crecyldiphenylphosphonite,cyclohexyldiphenylphosphonite, decyldiethylphosphonite,decyldimethylphosphonite, decyldiphenylphosphonite,dibutyl(2-methylphenyl)phosphonite, dicyclohexylphenylphosphonite,diethyl(3-methylphenyl)phosphonite, ethyldibutylphosphonite,ethyldimethylphosphonite, ethyldioctylphosphonite,ethyldiphenylphosphonite, ethyldipropylphosphonite,heptyldibutylphosphonite, heptyldiethylphosphonite, heptyldimethylphosphonite, heptyldipentylphosphonite, heptyldiphenylphosphonite,hexyldibutylphosphonite, hexyldiethylphosphonite, hexyldimethylphosphonite, hexyldipentylphosphonite, hexyldiphenylphosphonite,methylbis(4-methylphenyl)phosphonite, methyldibutylphosphonite,methyldidecylphosphonite, methyldiethylphosphonite,methyldiphenylphosphonite, methyldipropylphosphonite,octyldimethylphosphonite, octyldiphenylphosphonite,pentyldibutylphosphonite, pentyldiethylphosphonite,pentyldimethylphosphonite, pentyldiphenylphosphonite,phenyldibutylphosphonite, phenyldiethylphosphonite,phenyldimethylphosphonite, phenyldipropylphosphonite,propyldibutylphosphonite, propyldimethylphosphonite,propyldiphenylphosphonite, tri(2-chloroethyl)phosphonite,tri(nonylphenyl)phosphonite, tris(2,3-dichloropropyl)phosphonite,tris(2,6-dimethylphenyl)phosphonite, tris(2-methylphenyl)phosphonite,tris(4-methylphenyl)phosphonite, tris(methoxyphenyl)phosphonite,tris[4-(1,1-dimethylethyl)phenyl]phosphonite, tri-t-butylphosphonite, orcombinations thereof. In some embodiments, the phosphonites suitable foruse in this disclosure include without limitation tributylphosphonite,tricresyl phosphonite, tricyclohexyl phosphonite, tridecylphosphonite,triethylphosphonite, triheptylphosphonite, triisopropylphosphonite,trimethylphosphonite, trioctadecyl phosphonite, trioctylphosphonite,tripentylphosphonite, triphenylphosphonite, tripropylphosphonite,tritolylphosphonite, trixylylphosphonite, or combinations thereof. In anembodiment, the organophosphorus compound and/or organophosphoruscompound precursor may be present in the mixture for the preparation ofthe PPSC in an amount of from about 0.005 wt. % to about 5 wt. % basedon the weight of phosphorus to the total weight of the PPSC,alternatively from about 0.01 wt. % to about 1 wt. %, alternatively fromabout 0.05 wt. % to about 0.5 wt. %. The amount of organophosphoruscompound and/or phosphorus incorporated into the PPSC may be in therange described herein for the amount of organophosphorus compoundand/or precursor used to prepare the PPSC.

In an embodiment, the PPSC may further comprise one or more selectivityenhancers. Suitable selectivity enhancers include, but are not limitedto, Group 1B metals, Group 1B metal compounds, silver compounds,fluorine, fluoride compounds, sulfur, sulfur compounds, alkali metals,alkali metal compounds, alkaline metals, alkaline metal compounds,iodine, iodide compounds, or combinations thereof. In an embodiment, thePPSC comprises one or more selectivity enhancers which may be present intotal in the mixture for preparation of the PPSC in an amount of fromabout 0.001 to about 10 wt. % based on the total weight of the PPSC,alternatively from about 0.01 to about 5 wt. %, alternatively from about0.01 to about 2 wt. %. The amount of selectivity enhancer incorporatedinto the PPSC may be in the range described herein for the amount ofselectivity enhancer used to prepare the PPSC.

In an embodiment, the selectivity enhancer comprises silver (Ag), silvercompounds, or combinations thereof. Examples of suitable silvercompounds include without limitation silver nitrate, silver acetate,silver bromide, silver chloride, silver iodide, silver fluoride, orcombinations thereof. In an embodiment, the selectivity enhancercomprises silver nitrate. The PPSC may be prepared using silver nitratein an amount of from about 0.005 wt. % to about 5 wt. % silver based onthe total weight of the PPSC, alternatively from about 0.01 wt. % toabout 1 wt. % silver, alternatively from about 0.05 wt. % to about 0.5wt. %. The amount of silver incorporated into the PPSC may be in therange described herein for the amount of silver nitrate used to preparethe PPSC.

In an embodiment, the selectivity enhancer comprises alkali metals,alkali metal compounds, or combinations thereof. Examples of suitablealkali metal compounds include without limitation elemental alkalimetal, alkali metal halides (e.g., alkali metal fluoride, alkali metalchloride, alkali metal bromide, alkali metal iodide), alkali metaloxides, alkali metal carbonate, alkali metal sulfate, alkali metalphosphate, alkali metal borate, or combinations thereof. In anembodiment, the selectivity enhancer comprises potassium fluoride (KF).In another embodiment, the PPSC is prepared using an alkali metalcompound in an amount of from about 0.01 wt. % to about 5 wt. % based onthe total weight of the PPSC, alternatively from about 0.05 wt. % toabout 2 wt. %, alternatively from about 0.1 wt. % to about 1 wt. %. Theamount of alkali metal incorporated into the PPSC may be in the rangedescribed herein for the amount of alkali metal compound used to preparethe PPSC.

In an embodiment, a method of preparing a PPSC may initiate with thecontacting of an inorganic support with a palladium-containing compoundto form a supported palladium composition. The contacting may be carriedout using any suitable technique. For example, the inorganic support maybe contacted with the palladium-containing compound by incipient wetnessimpregnation of the support with a palladium-containing solution. Insuch embodiments, the resulting supported palladium composition may havegreater than about 90 wt %, alternatively from about 92 wt % to about 98wt %, alternatively from about 94 wt % to about 96% of the palladiumconcentrated near the periphery of the palladium supported composition,as to form a palladium skin.

The palladium skin can be any thickness as long as such thickness canpromote the hydrogenation processes disclosed herein. Generally, thethickness of the palladium skin can be in the range of from about 1micron to about 3000 microns, alternatively from about 5 microns toabout 2000 microns, alternatively from about 10 microns to about 1000microns, alternatively from about 50 microns to about 500 microns.Examples of such methods are further described in more details in U.S.Pat. Nos. 4,404,124 and 4,484,015, each of which is incorporated byreference herein in its entirety.

Any suitable method may be used for determining the concentration of thepalladium in the skin of the palladium supported composition and/or thethickness of the skin. For example, one method involves breaking open arepresentative sample of the palladium supported composition particlesand treating the palladium supported composition particles with a dilutealcoholic solution of N,N-dimethyl-para-nitrosoaniline. The treatingsolution reacts with the palladium to give a red color that can be usedto evaluate the distribution of the palladium. Yet another technique formeasuring the concentration of the palladium in the skin of thepalladium supported composition involves breaking open a representativesample of catalyst particles, followed by treating the particles with areducing agent such as hydrogen to change the color of the skin andthereby evaluate the distribution of the palladium. Alternatively, thepalladium skin thickness may be determined using the electron microprobemethod.

The supported palladium composition formed by contacting the inorganicsupport with the palladium-containing solution optionally may be driedat a temperature of from about 15° C. to about 150° C., alternativelyfrom about 30° C. to about 100° C., alternatively from about 60° C. toabout 100° C.; and for a period of from about 0.1 hour to about 100hours, alternatively from about 0.5 hour to about 20 hours,alternatively from about 1 hour to about 10 hours. Alternatively, thepalladium supported composition may be calcined. This calcining step canbe carried out at temperatures up to about 850° C., alternatively offrom about 150° C. to about 700° C., alternatively from about 150° C. toabout 600° C., alternatively from about 150° C. to about 500° C.; andfor a period of from about 0.2 hour to about 20 hours, alternativelyfrom about 0.5 hour to about 20 hours, alternatively from about 1 hourto about 10 hours.

In an embodiment, a method of preparing a PPSC further comprisescontacting the supported palladium composition with an organophosphoruscompound of the type described herein (e.g., phosphine oxide, phosphate,an organophosphorus compound precursor such as an phosphate or anphosphine). The contacting may be carried out in any suitable mannerthat will yield a selective hydrogenation catalyst meeting theparameters described herein such as for example by incipient wetnessimpregnation. Briefly, the organophosphorus compound may comprisephosphine oxide which is dissolved in a solvent, such as for example,water, acetone, isopropanol, etc., to form a phosphine oxide containingsolution. The supported palladium composition may be added to thephosphine oxide containing solution to form a palladium/phosphine oxidesupported composition (herein this particular embodiment of the PPSC isreferred to as a Pd/PO composition).

In some embodiments, one or more selectivity enhancers of the typedescribed previously herein may be added to the supported palladiumcomposition prior to or following the contacting of same with anorganophosphorus compound. In an embodiment, this addition can occur bysoaking the supported palladium composition (with or without theorganophosphorus compound) in a liquid comprising one or more suitableselectivity enhancers. In another embodiment, this addition can occur byincipient wetness impregnation of the supported palladium composition(with or without an organophosphorus compound) with liquid comprisingone or more suitable selectivity enhancers to form an enhanced supportedpalladium composition.

In an embodiment, silver may be added to the supported palladiumcomposition (without an organophosphorus compound). For example, thesupported palladium composition can be placed in an aqueous silvernitrate solution of a quantity greater than that necessary to fill thepore volume of the composition. The resulting material is apalladium/silver supported composition (herein this particularembodiment of the PPSC is referred to as a Pd/Ag composition). In anembodiment, the Pd/Ag composition is further contacted with anorganophosphorus compound. The contacting may be carried out asdescribed above to form a palladium/silver/phosphine oxide composition.In another embodiment, the Pd/Ag composition is further contacted with aphosphine oxide compound (herein this particular embodiment of the PPSCis referred to as a Pd/Ag/PO composition).

In an embodiment, one or more alkali metals may be added to the Pd/Agcomposition (prior to or following contacting with an organophosphoruscompound) using any suitable technique such as those describedpreviously herein. In an embodiment, the selectivity enhancer comprisespotassium fluoride, and the resulting material is apalladium/silver/alkali metal fluoride supported composition (hereinthis particular embodiment of the PPSC is referred to as a Pd/Ag/KFcomposition).

In an embodiment, the supported palladium composition is contacted withboth an alkali metal halide and a silver compound (prior to or followingcontacting with an organophosphorus compound). Contacting of thesupported palladium composition with both an alkali metal halide and asilver compound may be carried out simultaneously; alternatively thecontacting may be carried out sequentially in any user-desired order.

In an embodiment, one or more selectivity enhancers are contacted withthe supported palladium composition prior to contacting the compositionwith an organophosphorus compound. In such embodiments, the resultingcomposition comprising Pd/Ag, Pd/KF, or Pd/Ag/KF may be calcined underthe conditions described previously herein, and subsequently contactedwith an organophosphorus compound. For example, phosphine oxide (PO) maybe added to the Pd/Ag, Pd/KF, and/or Pd/Ag/KF compositions to providePd/Ag/PO, Pd/KF/PO, and/or Pd/Ag/KF/PO compositions. In an alternativeembodiment, one or more selectivity enhancers are contacted with thesupported palladium composition following contacting of the compositionwith an organophosphorus compound. For example, Ag and/or KF may beadded to the Pd/PO composition to provide Pd/Ag/PO, Pd/KF/PO, and/orPd/Ag/KF/PO compositions. In yet another alternative embodiment, one ormore selectivity enhancers may be contacted with the palladium supportedcomposition and an organophosphorus compound simultaneously.

In an embodiment, a PPSC formed in accordance with the methods disclosedherein comprises an α-alumina support, palladium, and anorganophosphorus compound. In an alternative embodiment, a PPSC formedin accordance with the methods disclosed herein comprises an α-aluminasupport, palladium, an organophosphorus compound (e.g., phosphine oxide)and one or more selectivity enhancers, (e.g., silver and/or potassiumfluoride). The PPSC (Pd/PO, Pd/Ag/PO, Pd/KF/PO, and/or the Pd/Ag/KF/POcompositions) can be dried to form a dried PPSC. In some embodiments,this drying step can be carried out at a temperature in the range offrom about 0° C. to about 150° C., alternatively from about 30° C. toabout 100° C., alternatively from about 50° C. to about 80° C.; and fora period of from about 0.1 hour to about 100 hours, alternatively fromabout 0.5 hour to about 20 hours, alternatively from about 1 hour toabout 10 hours. In an embodiment, the organophosphorus compoundcomprises an organophosphorus compound precursor which upon exposure toair and/or the temperature ranges used during drying of theaforementioned composition is converted to an organophosphorus compoundof the type described herein.

The dried PPSC may be reduced using hydrogen gas or a hydrogen gascontaining feed, e.g., the feed stream of the selective hydrogenationprocess, thereby providing for optimum operation of the selectivehydrogenation process. Such a gaseous hydrogen reduction may be carriedout at a temperature in the range of from, for example, about 0° C. toabout 150° C., alternatively 30° C. to about 100° C., alternativelyabout 50° C. to about 80° C.

In an embodiment, a method of preparing a PPSC comprises contacting aninorganic support with a palladium-containing compound (e.g., palladiumchloride, palladium nitrate) to form a palladium supported composition;drying and calcining the palladium supported composition to form a driedand calcined palladium supported composition. The dried and calcinedpalladium supported composition may then be contacted with asilver-containing compound (e.g., silver nitrite, silver fluoride) toform a Pd/Ag composition which may then be dried and/or calcined to forma dried and/or calcined Pd/Ag composition. The dried and/or calcinedPd/Ag composition may be contacted with an alkali metal fluoride (e.g.,potassium fluoride) to form a Pd/Ag/KF composition which is then driedand calcined. The dried and calcined Pd/Ag/KF composition may then becontacted with an organophosphorus compound (e.g., phosphine oxide orprecursor) to form a PPSC. In an alternative embodiment, the Pd/Ag/KFcomposition may be added to an unsaturated hydrocarbon and theorganophosphorus compound may be separately added to the unsaturatedhydrocarbon so that the Pd/Ag/KF composition contacts theorganophosphorus compound to form the PPSC while in contact with theunsaturated hydrocarbon. The PPSC may be further processed by drying thePPSC to form a dried PPSC. The contacting, drying, and calcining may becarried out using any suitable technique and conditions such as thosedescribed previously herein.

In an embodiment, the PPSC catalyses a selective hydrogenation process.In such processes the PPSC may be contacted with an unsaturatedhydrocarbon stream primarily containing unsaturated hydrocarbons, e.g.,ethylene, but also containing a highly unsaturated hydrocarbon, e.g.,acetylene. The contacting may be executed in the presence of hydrogen atconditions effective to selectively hydrogenate the highly unsaturatedhydrocarbon to an unsaturated hydrocarbon. In an embodiment, the PPSCsof the type disclosed herein are used in the hydrogenation of highlyunsaturated hydrocarbons such as for example and without limitationacetylene, methylacetylene, propadiene, butadiene or combinationsthereof.

FIG. 1 illustrates an embodiment of a hydrogenation process thatutilizes a PPSC of the type disclosed herein. The hydrogenation processincludes feeding an unsaturated hydrocarbon stream 10 and a hydrogen(H₂) stream 20 to a hydrogenation reactor 30 within which the PPSC isdisposed. The unsaturated hydrocarbon stream 10 primarily comprises oneor more unsaturated hydrocarbons, but it may also contain one or morehighly unsaturated hydrocarbons such as for example and withoutlimitation acetylene, methylacetylene, propadiene, and butadiene.Alternatively, unsaturated hydrocarbon stream 10 and hydrogen stream 20may be combined in a single stream that is fed to hydrogenation reactor30.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatmay belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a backend configuration. As used herein, “backend”refers to the location of the acetylene removal unit in an unsaturatedhydrocarbon production unit that receives the lower boiling fractionfrom a deethanizer fractionation tower that receives the higher boilingfraction from a demethanizer fractionation tower which receives a feedfrom an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatmay belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a frontend deethanizer configuration. As usedherein, “frontend deethanizer” refers to the location of the acetyleneremoval unit in an unsaturated hydrocarbon production unit that receivesthe lower boiling fraction from a deethanizer fractionation tower thatreceives a feed from an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatmay belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a frontend depropanizer configuration. As usedherein, “frontend depropanizer” refers to the location of the acetyleneremoval unit in an unsaturated hydrocarbon production unit that receivesthe lower boiling fraction from a depropanizer fractionation tower thatreceives a feed from an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatmay belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a raw gas configuration. As used herein, “raw gas”refers to the location of the acetylene removal unit in an unsaturatedhydrocarbon production unit that receives a feed from an unsaturatedhydrocarbon production process without any intervening hydrocarbonfractionation.

It is understood that hydrogenation reactor 30, and likewise theselective hydrogenation catalysts disclosed herein, are not limited touse in backend acetylene removal units, frontend deethanizer units,frontend depropanizer, or raw gas units and may be used in any processwherein a highly unsaturated hydrocarbons contained within anunsaturated hydrocarbon stream is selectively hydrogenated to aunsaturated hydrocarbon.

In those embodiments wherein the acetylene removal unit is in a backendconfiguration, the highly unsaturated hydrocarbon being fed to thehydrogenation reactor 30 comprises acetylene. The mole ratio of thehydrogen to the acetylene being fed to hydrogenation reactor 30 may bein the range of from about 0.1 to about 10, alternatively from about 0.2to about 5, alternatively from about 0.5 to about 3.

In those embodiments wherein the acetylene removal unit is in a frontend deethanizer, front-end depropanizer or raw gas configuration, thehighly unsaturated hydrocarbon being fed to the hydrogenation reactor 30comprises acetylene. In such an embodiment, the mole ratio of thehydrogen to the acetylene being fed to the hydrogenation reactor 30 maybe in the range of from about 10 to about 3000, alternatively from about10 to about 2000, alternatively from about 10 to about 1500.

In those embodiments wherein the acetylene removal unit is in afront-end depropanizer or raw gas configuration, the highly unsaturatedhydrocarbon being fed to the hydrogenation reactor 30 comprisesmethylacetylene. In such an embodiment, the mole ratio of the hydrogento the methylacetylene being fed to the hydrogenation reactor 30 may bein the range of from about 3 to about 3000, alternatively from about 5to about 2000, alternatively from about 10 to about 1500.

In those embodiments wherein the acetylene removal unit is in afront-end depropanizer or raw gas configuration, the highly unsaturatedhydrocarbon being fed to the hydrogenation reactor 30 comprisespropadiene. In such an embodiment, the mole ratio of the hydrogen to thepropadiene being fed to the hydrogenation reactor 30 may be in the rangeof from about 3 to about 3000, alternatively from about 5 to about 2000,alternatively from about 10 to about 1500.

In another embodiment, reactor 30 may represent a plurality of reactors.The plurality of reactors may optionally be separated by a means toremove heat produced by the reaction. The plurality of reactors mayoptionally be separated by a means to control inlet and effluent flowsfrom reactors or heat removal means allowing for individual oralternatively groups of reactors within the plurality of reactors to beregenerated. The selective hydrogenation catalyst may be arranged in anysuitable configuration within hydrogenation reactor 30, such as a fixedcatalyst bed.

Carbon monoxide may also be fed to reactor 30 via a separate stream (notshown), or it may be combined with hydrogen stream 20. In an embodiment,the amount of carbon monoxide being fed to reactor 30 during thehydrogenation process is less than about 0.15 mol % based on the totalmoles of fluid being fed to reactor 30.

Hydrogenation reactor 30 may be operated at conditions effective toselectively hydrogenate highly unsaturated hydrocarbons to one or moreunsaturated hydrocarbons upon contacting the selective hydrogenationcatalyst in the presence of the hydrogen. The conditions are desirablyeffective to maximize hydrogenation of highly unsaturated hydrocarbonsto unsaturated hydrocarbons and to minimize hydrogenation of highlyunsaturated hydrocarbons to saturated hydrocarbons. In some embodiments,acetylene may be selectively hydrogenated to ethylene. Alternativelymethylacetylene may be selectively hydrogenated to propylene;alternatively propadiene may be selectively hydrogenated to propylene.Alternatively butadiene may be selectively hydrogenated to butenes. Insome embodiments, the temperature within the hydrogenation zone may bein the range of from about 5° C. to about 300° C., alternatively fromabout 10° C. to about 250° C., alternatively from about 15° C. to about200° C. In some embodiments, the pressure within the hydrogenation zonemay be in the range of from about 15 (204 kPa) to about 2,000 (13,890kPa) pounds per square inch gauge (psig), alternatively from about 50psig (446 kPa) to about 1,500 psig (10,443 kPa), alternatively fromabout 100 psig (790 kPa) to about 1,000 psig (6,996 kPa).

Referring back to FIG. 1, an effluent stream 40 comprising unsaturatedhydrocarbons, including the one or more monoolefins produced inhydrogenation reactor 30, and any unconverted reactants exithydrogenation reactor 30. In an embodiment, effluent stream 40 primarilycomprises ethylene comprises less than about 5 ppm, alternatively lessthan about 1 ppm of highly unsaturated hydrocarbons.

In an embodiment, a PPSC of the type describe herein may have acomparable catalytic activity when compared to an otherwise similarcatalyst lacking an organophosphorus compound. The comparable catalyticactivity may translate to a comparable clean up temperature. Herein, theclean up temperature is referred to as T1 and refers to the temperatureat which the acetylene concentration drops below 20 ppm in a feed streamcomprising unsaturated hydrocarbon and highly unsaturated hydrocarbonssuch as acetylenes and diolefins. In an embodiment, a PPSC of the typedisclosed herein may have a T1 of from about 80° F. to about 160° F.,alternatively from about 85° F. to about 140° F., alternatively fromabout 90° F. to about 120° F.

In an embodiment, a PPSC may exhibit an increased selectivity whencompared to an otherwise similar catalyst lacking an organophosphoruscompound of the type described herein. Herein selectivity refers to acomparison between the rate at which the catalyst converts a highlyunsaturated hydrocarbon to an unsaturated hydrocarbon, herein termedConversion 1, and the rate at which the catalyst converts an unsaturatedhydrocarbon to a saturated hydrocarbon, herein termed Conversion 2. APPSC may display an increased rate of Conversion 1 and a decreased rateof Conversion 2 when compared to an otherwise similar catalyst preparedin the absence of an organophosphorus compound of the type describedherein. Conversion 2 is highly exothermic and can lead to runawayreactions or the uncontrollable conversion of unsaturated hydrocarbonsto saturated hydrocarbons. The higher selectivity of the PPSC may resultin a reduction in the incidence of runaway reactions and increase theoperating window of the hydrogenation process.

An operating window (ΔT) is defined as the difference between a runawaytemperature (T2) at which 3 wt % of ethylene is hydrogenated from afeedstock comprising highly unsaturated and unsaturated hydrocarbons,and the clean up temperature (T1). ΔT is a convenient measure of thecatalyst selectivity and operation stability in the hydrogenation ofhighly unsaturated hydrocarbons (e.g., acetylene) to unsaturatedhydrocarbons (e.g., ethylene). The more selective a catalyst, the higherthe temperature beyond T1 required to hydrogenate a given unsaturatedhydrocarbons (e.g., ethylene). The T2 is coincident with the temperatureat which a high probability of runway ethylene hydrogenation reactioncould exist in an adiabatic reactor. Therefore, a larger ΔT translatesto a more selective catalyst and a wider operation window for thecomplete acetylene hydrogenation.

In an embodiment, a PPSC of the type disclosed herein may have anoperating window of from about 35° F. to about 120° F., alternativelyfrom about 40° F. to about 80° F., alternatively from about 45° F. toabout 60° F. The operating window of a PPSC of the type described hereinmay be increased by greater than about 10%, alternatively greater thanabout 15%, alternatively greater than about 20% when compared to anotherwise similar catalyst prepared in the absence of anorganophosphorus compound.

In an embodiment, a PPSC of the type described herein when used as ahydrogenation catalyst produces a reduced amount of heavies. As usedherein, heavies refer to molecules having four or more carbon atoms permolecule. Selective hydrogenation catalysts can produce heavies byoligomerizing the highly unsaturated hydrocarbons (e.g., acetylenes anddiolefins) that are present in the feed stream. The presence of heaviesis one of a number of contributors to the fouling of the selectivehydrogenation catalysts that result in catalyst deactivation. Thedeactivation of the selective hydrogenation catalyst results in thecatalyst having a lower activity and selectivity to unsaturatedhydrocarbons. In an embodiment, a PPSC of the type described hereinexhibits a reduction in the weight percent of wt % C4+ produced at T1 offrom about 1 wt. % to about 25 wt. % alternatively from about 1.5 wt. %to about 20 wt. % alternatively from about 2 wt. % to about 15 wt. %.

In an embodiment, a PPSC comprises an organophosphorus compound having alow boiling point as described previously herein. Herein, theorganophosphorus compound having a low boiling point is referred to asan LBP organophosphorus compound. In such embodiments, the PPSC maydisplay activity comparable to or greater than an otherwise similarcatalyst prepared in the absence of an organophosphorus compound. In anembodiment, a hydrogenation catalyst comprising a palladium supportedcatalyst composition with an LBP organophosphorus compound of the typedescribed herein may result in the catalyst displaying a selectivity andactivity comparable to that of a hydrogenation catalyst comprising oneor more selectivity enhancers (e.g., Pd/Ag, Pd/KF, or Pd/Ag/KF). Inanother embodiment, treatment of a hydrogenation catalyst comprising asingle selectivity enhancer (e.g., Pd/Ag or Pd/KF) with an LBPorganophosphorus compound of the type described herein may result in thecatalyst displaying a selectivity and activity comparable to that of ahydrogenation catalyst comprising at least two selectivity enhancers(e.g., Pd/Ag/KF).

A method for the selective hydrogenation of a hydrocarbon feedcomprising highly unsaturated and unsaturated hydrocarbons may comprisethe preparation of a PPSC catalyst comprising a LBP organophosphoruscompound and contacting of the PPSC with the hydrocarbon feed in areactor having an initial temperature (T0). The LBP organophosphoruscompound may remain associated with the PPSC upon start of the reactionat T0, however, over time and as the temperature increases above theboiling point of the LBP organophosphorus compound, the LBPorganophosphorus compound may be evaporated (i.e., boiled off) from thePPSC. The PPSC comprising the LBP organophosphorus compound may displayan increased activity over some time period and enhanced initialselectivity wherein the LBP organophosphorus compound is associated withthe PPSC. This may be advantageous for reactions employing a freshcatalyst as the LBP organophosphorus compound may allow for a morestable operation and a reduction in the potential for a runaway reactiondue to the increase in catalyst selectivity and predictable catalyticactivity as the composition stabilizes. Following the loss of the LBPorganophosphorus compound, the resulting composition may display anactivity and selectivity comparable to that of an otherwise similarcatalyst prepared in the absence of an organophosphorus compound.

In an alternative embodiment, a method for the selective hydrogenationof a hydrocarbon feed comprising highly unsaturated and unsaturatedhydrocarbons comprises the preparation of a PPSC comprising a highboiling point organophosphorus compound of the type described previouslyherein and contacting of the PPSC with the hydrocarbon feed. The highboiling point organophosphorus compound may remain associated with thePPSC throughout the lifetime of the catalyst providing the reactiontemperature remains below the boiling point of the high boiling pointorganophosphorus compound. The PPSC comprising the high boiling pointorganophosphorus compound may display improvements in characteristicssuch as catalytic activity and selectivity when compared to an otherwisesimilar catalyst composition prepared in the absence of anorganophosphorus compound.

EXAMPLES

The disclosure having been generally described, the following examplesare given as particular embodiments of the disclosure and to demonstratethe practice and advantages thereof. It is understood that the examplesare given by way of illustration and are not intended to limit thespecification of the claims to follow in any manner.

In the following examples, the performance of various PPSCs was comparedto similar catalysts lacking an organophosphorus compound. Each catalystcontained palladium (Pd) and an alumina support. Additional catalystdetails are found in each example. The catalyst was evaluated by placing20 ml of catalyst sample inside a stainless steel reactor with 0.65inches inside diameter. A thermowell of 3/16 inches diameter wasinserted through the catalyst bed. The reactor temperature was regulatedby circulating a heating medium, which contained a mixture of ethyleneglycol and water, over the exterior surface of the reactor. The catalystwas first reduced at about 100° F. to 200° F. for about 1 to 2 hoursunder hydrogen gas flowing at 200 ml/min at 200 pounds per square inchgauge (psig). There, a hydrocarbon containing fluid, typically a feedfrom the top of a deethanizer or depropanizer fractionation tower in anethylene plant, containing hydrogen, methane, ethane, ethylene,acetylene, and carbon monoxide was continuously introduced to thereactor at a flow rate of 900 mL per minute at 200 psig. The reactortemperature was increased until the hydrogenation reaction ran away,i.e., the uncontrollable hydrogenation of ethylene was allowed to occur.During the runaway, the heat of hydrogenation built up such that thereactor temperature exceeded about 250° F. The reactor was then allowedto cool to room temperature before data collection was started.

Feed (900 mL/min at 200 psig) was passed over the catalyst continuouslywhile holding the temperature constant before sampling the exit streamby gas chromatography. The catalyst temperature was determined byinserting a thermocouple into the thermowell and varying its positionuntil the highest temperature was observed. The temperature of theheating medium was then raised a few degrees, and the testing cycle wasrepeated until 3 weight % of ethylene was hydrogenated. The cleanuptemperature, T1, and the operating window, ΔT were determined asdescribed previously. All temperatures are in degrees Fahrenheit.Further, the selectivity to heavies was calculated on a weight basisusing the following equation, where “heavies” refer to hydrocarbonshaving four or more carbon atoms:selectivity to heavies=(weight of heavies made/weight of acetyleneconsumed)*100

Example 1

The ability of various catalyst compositions to hydrogenate adeethanizer feed stream was investigated. A first control catalystsample, Catalyst A1, was prepared on α-Al₂O₃ pellets supplied by SüdChemie of Louisville, Ky., USA in the form of 4 mm×4 mm tablets asdescribed in U.S. Pat. No. 4,484,015 which is incorporated by referenceherein in its entirety. The α-Al₂O₃ pellets had a surface area of about5 to about 7 m²/g (determined by the BET method employing N₂). CatalystA1 contained 230 ppm by weight (ppmw) palladium and 920 ppmw silver.Catalyst A1 was evaluated for selective hydrogenation of acetylene usinga feed whose compositions is presented in Table 1 Catalyst A1 wasdetermined to have a T1 of 97° F., ΔT of 49° F., and C4+ make at T1 of19.5%.

TABLE 1 Reactor Feed Component Mol % Hydrogen 26.63 Methane 25.81Acetylene 0.1613 Ethylene 47.36 Carbon monoxide 0.0338

A second control sample, Catalyst A2 was prepared as follows: 0.220 g KFwas dissolved in water (H₂O) to form a 16.22 g solution which was usedto impregnate 50.06 g of Catalyst A1. Catalyst A2 was then dried at 90°C. for 1 hour, at 200° C. for 1 hour, at 300° C. for 1 hour, and at 400°C. for 3 hours resulting in a catalyst comprising 0.3 wt. % KF. Theperformance of Catalyst A2 was then tested in a selective hydrogenationprocess using a feed described in Table 1. T1, T2, and ΔT weredetermined and the results are tabulated in Table 2. Additionally,Catalyst A2 was found to have a C4+ make at T1 of 15.2%.

TABLE 2 T1 (° F.) 110 T2 (° F.) 174 ΔT (° F.) 64

Catalyst A3 was prepared as follows: 0.190 g triphenyl phosphine oxide(TPPO) was dissolved in acetone to form a 15.08 g solution which wasused to impregnate 50.53 g of Catalyst A1. Catalyst A3 was then airdried and purged overnight with a vacuum and contained 0.044 wt. % ofphosphorus. The Catalyst A3 was then used to selectively hydrogenate ahydrocarbon feed the components of which are presented in Table 1. T1,T2, and ΔT were determined and the results are tabulated in Table 3.Additionally, Catalyst A3 has a C4+ make at T1 of 12.8%. Catalyst A3prepared using a phosphine oxide (i.e., TPPO) has a slightly broaderoperation window than either of the control samples (Catalysts A1 orA2), further Catalyst A3 produced a reduced amount of heavies at T1 thaneither control sample.

TABLE 3 T1 (° F.) 102 T2 (° F.) 167 ΔT (° F.) 65

Catalyst A4 was prepared as follows: 0.099 g of TPPO was dissolved inisopropanol to form a 7.5 g solution which was used to impregnate 25.35g Catalyst A2. Catalyst A4 was then air dried and placed in an oven at100° C. for 3 hours. Catalyst A4 contained 0.044 wt. % of phosphorus.The performance of Catalyst A4 was tested in a selective hydrogenationprocess with a feed given in Table 1. T1, T2, and ΔT were determined andthe results are tabulated in Table 4. Additionally, Catalyst A4 has aC4+ make at T1 of 12.4%, which shows how much fouling agents areproduced at T1. Catalyst A4 displayed a broader operation window thaneither of the control catalyst samples prepared in the absence of anorganophosphorus compound and a reduced production of heavies.

TABLE 4 T1 (° F.) 113 T2 (° F.) 193 ΔT (° F.) 80

Catalyst A5 was prepared as follows: 0.383 g TPPO was dissolved inisopropanol to form a 16.86 g solution which was used to impregnate50.40 g of Catalyst A1. Catalyst A5 was air dried and then dried for 4hours in an oven at 100° C. Catalyst A5 contained 0.088 wt. % ofphosphorus. The performance of Catalyst A5 was tested in a selectivehydrogenation process. The reactor feed components are shown in Table 1.T1, T2, and ΔT were determined and the results are tabulated in Table 5.Additionally, Catalyst A5 has a C4+ make at T1 of 7.4%. Catalyst A5displayed a broader operation window than either of the control catalystsamples prepared in the absence of an organophosphorus compound and areduced production of heavies.

TABLE 5 T1 (° F.) 108 T2 (° F.) 183 ΔT (° F.) 75

Catalyst A6 was prepared as follows: 0.052 g triethyl phosphine oxide(TEPO) was dissolved in acetone to form a 18.5 g solution which was usedto impregnate 50.47 g of Catalyst A2. Catalyst A6 was then air dried andpurged overnight with a vacuum. The TEPO content in Catalyst A6 wasdetermined by ion coupled plasma (ICP) to be 253 ppmw (i.e., 0.025 wt.%) of phosphorus. The performance of Catalyst A6 was tested in aselective hydrogenation process. The reactor feed components aretabulated in Table 1. T1, T2, and ΔT for ethylene and ethane weredetermined and the results are tabulated in Table 6. Additionally,Catalyst A6 has a C4+ make at T1 of 25%. Catalyst A6 displayed a broaderoperation window than either of the control catalyst samples prepared inthe absence of an organophosphorus compound (i.e., TEPO) but displayed ahigher production of heavies which may be attributable to a variety offactors including for example analytical error.

TABLE 6 T1 (° F.) 109 T2 (° F.) 188 ΔT (° F.) 79

Catalyst A7 was prepared as follows: 0.081 g TEPO was dissolved inacetone to form a 15.33 g solution which was used to impregnate 50.63 gof Catalyst A1. Catalyst A7 was then air dried and purged overnight witha vacuum. Catalyst A7 contained 0.044 wt. % of phosphorus. Theperformance of Catalyst A7 was tested in a selective hydrogenationprocess. The reactor feed components are shown in Table 1. T1 and ΔTwere determined and the results are tabulated in Table 7. Additionally,Catalyst A7 has a C4+ make at T1 of 17% and spent Catalyst A7 wasdetermined to contain 356 ppmw phosphorus by ICP. Catalyst A7 displayeda broader operation window than either of the control catalyst samplesprepared in the absence of an organophosphorus compound.

TABLE 7 T1 (° F.) 99 T2 (° F.) 161 ΔT (° F.) 62

A comparison of catalyst components and performance in a deethanizer C2feed is shown in Table 8. Referring to Table 8, collectively, theresults demonstrated that the addition of organophosphorus compound(e.g., phosphine oxide) to a Pd/Ag or Pd/Ag/KF hydrogenation catalystincreased the operation window of the catalyst as was shown by comparingCatalyst A1 vs. A3 and A5, as well as Catalyst A2 vs. A4 and A6.

TABLE 8 Organo Tclean- Operation C4+ make Palladium Silver PotassiumPhosphorus Phosphorus up Window at Tclean- Catalyst (ppmw) (ppmw) (wt.%) (wt. %) compound (° F.) (° F.) up (%) A1 230 920 0 0 0 97 49 19.5 A2230 920 0.3 0 0 110 64 15.2 A3 230 920 0 0.044 TPPO 102 65 12.8 A4 230920 0.3 0.044 TPPO 113 80 12.4 A5 230 920 0 0.088 TPPO 108 75 7.4 A6 230920 0.3 0.025 TEPO 109 79 25

Example 2

Catalyst A8 was prepared from the same support as Catalyst A1 fromExample 1. Catalyst A8 contained 230 ppmw palladium and had no silver.The performance of Catalyst A8 was tested in a selective hydrogenationprocess. The reactor feed components are shown in Table 1. T1, T2, andΔT were determined and the results are tabulated in Table 9.Additionally, Catalyst A8 has a C4+ make at T1 of 31.6%.

TABLE 9 T1 (° F.) 98 T2 (° F.) 131 ΔT (° F.) 33

Catalyst A9 was prepared as follows: 0.381 g TPPO was dissolved inisopropanol to form a 16.31 g solution which was used to impregnate50.56 g of Catalyst A8. Catalyst A9 was air dried then dried in an ovenat 100° C. for 3 hours and found to contain 0.088 wt. % of phosphorus.The performance of Catalyst A9 was tested in a selective hydrogenationprocess. The reactor feed components are shown in Table 1. T1, T2, andΔT were determined and the results are tabulated in Table 10.Additionally, Catalyst A9 has a C4+ make at T1 of 23.7%. The resultsdemonstrate the presence of an organophosphorus compound (i.e., TPPO)broadened the catalyst window when compared to Catalyst A8.

TABLE 10 T1 (° F.) 96 T2 (° F.) 136 ΔT (° F.) 40

Catalyst A10 was prepared as follows: 0.164 g of 85% concentratedphosphoric acid was diluted with deionized water (DI H₂O) to form a 15 gsolution which was used to impregnate 50.36 g of Catalyst A1. CatalystA10 was air dried and then dried in an oven at 150° C. for 3 hours.Catalyst A10 contained 0.08 wt. % of phosphorus. The performance ofCatalyst A10 was tested in a selective hydrogenation process. Thereactor feed components are shown in Table 1. T1, T2, and ΔT weredetermined and the results are tabulated in Table 11. Additionally,Catalyst A10 has a C4+ make at T1 of 21.3%. The results demonstrate thepresence of phosphoric acid was ineffective when compared to an organicphosphine oxide (e.g., TPPO).

TABLE 11 T1 (° F.) 91 T2 (° F.) 131 ΔT (° F.) 40

A comparison for the components and performance of Catalysts A7-A10 isshown in Table 12. Referring to Table 12, collectively the resultsdemonstrated that the addition of an organic phosphine oxide to acatalyst increased the operation window of such catalyst as shown bycomparing Catalyst A8 vs. A9, A7, vs. A10.

TABLE 12 T Organo clean- Operation C4+ make Palladium Silver PotassiumPhosphorus Phosphorus up Window at Tclean- Catalyst (ppmw) (ppmw) (wt.%) (wt. %) compound (° F.) (° F.) up (%) A7 230 920 0 0.044 TEPO 99 6217.0% A8 230 0 0 0 0 98 33 31.6 A9 230 0 0 0.044 TPPO 96 40 23.7 A10 230920 0 0.08 Phosphoric 91 40 21.3 acid

Example 3

The performance of various catalysts was tested on a feed from adepropanizer. Catalyst B1 (control) was prepared on α-Al₂O₃ pelletssupplied by Süd Chemie of Louisville, Ky., USA in the form of 4 mm×4 mmtablets as described in U.S. Pat. No. 4,484,015. The α-Al₂O₃ pellets hada surface area of about 5 to about 7 m²/g (determined by the BET methodemploying N₂). Catalyst B1 contained 400 ppmw palladium and 400 ppmwsilver. The performance of Catalyst B1 was tested in a selectivehydrogenation process. The reactor feed components are shown in Table13.

TABLE 13 Reactor Feed Component mol % Hydrogen 21.98 Methane 45.13Acetylene 0.2340 Ethylene 26.09 Methylacetylene 0.0702 Propadiene 0.0780Propylene 6.40 Carbon monoxide 0.0233

T1, T2, and ΔT were determined and the results are tabulated in Table14. Additionally, Catalyst B1 has a C4+ make at T1 of 31.4%.

TABLE 14 T1 (° F.) 98 T2 (° F.) 140 ΔT (° F.) 42

Catalyst B2 was prepared from Catalyst B1 by addition of 0.1 wt. %potassium using potassium fluoride. The performance of Catalyst B2 wastested in a selective hydrogenation process. The reactor feed componentsare shown in Table 13. T1, T2, and ΔT were determined and the resultsare tabulated in Table 15. Additionally, Catalyst B2 has a C4+ make atT1 of 20.2%. Catalyst B2 displayed a broader operating window thanCatalyst B1.

TABLE 15 T1 (° F.) 102 T2 (° F.) 153 ΔT (° F.) 51

Catalyst B3 was prepared as follows: 1.534 g TPPO was dissolved with60.1 g isopropanol to form a solution which was used to impregnate 200.3g of Catalyst B1. Catalyst B3 contained 0.088 wt. % of phosphorus. Theperformance of Catalyst B3 was tested in a selective hydrogenationprocess using a feed shown in Table 13. T1, T2, and ΔT were determinedand the results are tabulated in Table 16. Additionally, Catalyst B3 hasa C4+ make at T1 of 6.0%. Catalyst B3 displayed a broader operationwindow and a reduced formation of heavies than either of the controlcatalyst samples prepared in the absence of an organophosphorus compound(i.e., TPPO).

TABLE 16 T1 (° F.) 102 T2 (° F.) 171 ΔT (° F.) 69

Catalyst B4 was prepared as follows: 1.541 g of TPPO was dissolved inisopropanol to form a solution which was used to impregnate 200.3 g ofCatalyst B2. Catalyst B4 was then air dried and placed overnight in anoven at 80° C. Catalyst B4 contained 0.088 wt. % of phosphorus. Theperformance of Catalyst B4 was tested in a selective hydrogenationprocess using the feed shown in Table 13. T1, T2, and ΔT were determinedand the results are tabulated in Table 17. Additionally, Catalyst B4 hasa C4+ make at T1 of 14.9%. Catalyst B3 displayed a broader operationwindow and a reduced formation of heavies than either of the controlcatalyst samples prepared in the absence of an organophosphorus compound(i.e., TPPO). Catalyst B4 also displayed a broader processing windowthan Catalyst B3. Without wishing to be limited by theory, the broaderoperation window displayed by Catalyst B4 may be attributable to thesynergy effect between the amounts of palladium, silver, phosphorus, andthe organophosphorus compound with the alkali metal.

TABLE 17 T1 (° F.) 104 T2 (° F.) 218 ΔT (° F.) 114

A comparison of the components and performance of Catalysts B1-B4 in adepropanizer for C3 feed is shown in Table 18. The results demonstratedthat the addition of organophosphorus compound to a catalyst increasedthe operation window of such catalyst as shown by comparing Catalyst B1vs. B3 and Catalyst B2 vs. B4.

TABLE 18 Organo Tclean- Operation C4+ make Palladium Silver PotassiumPhosphorus Phosphorus up Window at Tclean- Catalyst (ppmw) (ppmw) (wt.%) (wt. %) compound (° F.) (° F.) up (%) B1 400 400 98 42 31.4 B2 400400 0.1 102 51 20.2 B3 400 400 0.088 TPPO 102 69 6.0 B4 400 400 0.10.088 TPPO 104 114 14.9

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). Use of theterm “optionally” with respect to any element of a claim is intended tomean that the subject element is required, or alternatively, is notrequired. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the embodiments of the present invention. Thedisclosures of all patents, patent applications, and publications citedherein are hereby incorporated by reference, to the extent that theyprovide exemplary, procedural or other details supplementary to thoseset forth herein.

What is claimed is:
 1. A method of selectively hydrogenating highlyunsaturated hydrocarbons to an unsaturated hydrocarbon enrichedcomposition comprising: contacting the highly unsaturated hydrocarbonsand hydrogen in a reaction zone with a catalyst comprising palladium andan organophosphorus compound under conditions suitable for hydrogenatingat least a portion of the highly unsaturated hydrocarbons to unsaturatedhydrocarbons to produce the unsaturated hydrocarbon enrichedcomposition.
 2. The method of claim 1 wherein the highly unsaturatedhydrocarbons comprise acetylene, methylacetylene, propadiene, butadiene,or combinations thereof.
 3. The method of claim 2 wherein theunsaturated hydrocarbon enriched composition comprises less than about 5ppm of highly unsaturated hydrocarbons.
 4. The method of claim 1 whereinthe contacting occurs at a temperature less than about the boiling pointof the organophosphorus compound.
 5. The method of claim 4, furthercomprising increasing the temperature to equal to or greater than aboutthe boiling point of the organophosphorus compound.
 6. The method ofclaim 1 wherein the contacting occurs at a temperature of from about 5°C. to about 300° C.
 7. The method of claim 1 wherein the contactingoccurs at a temperature of about 80° F. to about 160° F. and theunsaturated hydrocarbon enriched composition comprises less than about20 ppm highly unsaturated hydrocarbons.
 8. The method of claim 1 whereinthe contacting occurs in an operating window of from about 35° F. toabout 120° F.
 9. The method of claim 1 wherein the contacting occurs inan operating window increased by greater than about 10% in comparison toan otherwise similar method performed with a catalyst lacking theorganophosphorus compound.
 10. The method of claim 1 wherein aselectivity for hydrogenation of the highly unsaturated hydrocarbons tothe unsaturated hydrocarbons is improved in comparison to an otherwisesimilar method performed with a catalyst lacking the organophosphoruscompound.
 11. The method of claim 1 wherein the contacting produces fromabout 1 wt. % to about 25 wt. % less C4+ material than an otherwisesimilar composition prepared with a catalyst lacking theorganophosphorus compound.
 12. The method of claim 1 wherein theselective hydrogenation of the highly unsaturated hydrocarbons to anunsaturated hydrocarbon enriched composition is performed in a backendacetylene removal unit, a frontend deethanizer unit, a frontenddepropanizer unit, or a raw gas unit.
 13. The method of claim 12 whereinthe selective hydrogenation of the highly unsaturated hydrocarbons to anunsaturated hydrocarbon enriched composition is performed in a backendacetylene removal unit; the highly unsaturated hydrocarbons compriseacetylene; and a mole ratio of hydrogen to acetylene being fed to thereaction zone is in the range of from about 0.1 to about
 10. 14. Themethod of claim 12 wherein the selective hydrogenation of the highlyunsaturated hydrocarbons to an unsaturated hydrocarbon enrichedcomposition is performed in a frontend deethanizer unit, a frontenddepropanizer unit, or a raw gas unit; the highly unsaturatedhydrocarbons comprise acetylene; and a mole ratio of hydrogen toacetylene being fed to the reaction zone is in the range of from about10 to about
 3000. 15. The method of claim 12 wherein the selectivehydrogenation of the highly unsaturated hydrocarbons to an unsaturatedhydrocarbon enriched composition is performed in a frontend depropanizerunit or a raw gas unit; the highly unsaturated hydrocarbons comprisemethylacetylene; and a mole ratio of hydrogen to methylacetylene beingfed to the reaction zone is in the range of from about 3 to about 3000.16. The method of claim 12 wherein the selective hydrogenation of thehighly unsaturated hydrocarbons to an unsaturated hydrocarbon enrichedcomposition is performed in a frontend depropanizer unit or a raw gasunit; the highly unsaturated hydrocarbons comprise propadiene; and amole ratio of hydrogen to propadiene being fed to the reaction zone isin the range of from about 3 to about
 3000. 17. The method of claim 1wherein the organophosphorus compound is represented by the generalformula (R)_(x)(OR′)_(y)P═O, wherein x and y are integers ranging from 0to 3 and x plus y equals 3, wherein each R is hydrogen, a hydrocarbylgroup, or combinations thereof; and wherein each R′ is a hydrocarbylgroup; or wherein the organophosphorus compound is a product of anorganophosphorus compound precursor represented by the general formulaof (R)_(x)(OR′)_(y)P, wherein x and y are integers ranging from 0 to 3and x plus y equals 3, wherein each R is hydrogen, a hydrocarbyl group,or combinations thereof; and wherein each R′ is a hydrocarbyl group. 18.The method of claim 17 wherein the organophosphorus compound comprises aphosphine oxide, phosphinate, phosphonate, phosphate, or combinationsthereof; or wherein the organophosphorus compound precursor comprises aphosphite, a phosphonite, a phosphinite, a phosphine, an organicphosphine, or combinations thereof.
 19. The method of claim 1 whereinthe catalyst further comprises one or more selectivity enhancersselected from the group consisting of Group 1B metals, Group 1B metalcompounds, silver compounds, fluorine, fluoride compounds, sulfur,sulfur compounds, alkali metal, alkali metal compounds, alkaline earthmetals, alkaline earth metal compounds, iodine, iodide compounds, andcombinations thereof.
 20. The method of claim 1 wherein the catalyst issupported and the support has a surface area of from about 2 m²/g toabout 100 m²/g, and greater than about 90 wt. % of the palladium isconcentrated near a periphery of the support.
 21. The method of claim 1wherein the catalyst is prepared by a method comprising: contacting asupport with a palladium-containing compound to form a palladiumsupported composition; contacting the palladium supported compositionwith an organophosphorus compound to form a catalyst precursor; andreducing the catalyst precursor to form the catalyst.